Installing Catalina and Troubleshooting Startup

Chapter 4 — Installing Catalina and Troubleshooting Startup

4.1 Starting the Mac From the USB Installer

With the bootable Catalina installer prepared, the next step is to start the Mac mini from the USB drive.

1. Shut down the Mac mini completely.
2. Connect the USB installer directly to the Mini, if possible.
3. Connect a keyboard, mouse, and display.
4. Turn on the Mini and immediately press and hold the Option (⌥) key.
5. Continue holding Option until the Startup Manager appears.
6. Select Install macOS Catalina.
7. Press Return or click the arrow to start from the installer.

On an Apple keyboard, Option is labeled option or ⌥. On many PC keyboards, the equivalent startup key is Alt.

Important: A keyboard that works after macOS starts may not function properly during startup. If the Startup Manager doesn't appear, try a wired USB keyboard connected directly to the Mini.

4.2 Our First Problem: The Installer Wouldn't Boot

Our first attempt did not go according to plan.

We had created the installation USB, but the Mini wasn't starting from it.

The original wireless keyboard was not cooperating with startup selection.

After troubleshooting, we tried a brand-new keyboard.

That keyboard allowed us to select the USB installer and proceed.

What we learned: Before rebuilding installation media or assuming a USB drive is defective, verify that the keyboard can send startup commands.

The replacement keyboard later became intermittently unresponsive during normal use. That was a separate problem; it had already worked for startup selection.

4.3 Open Disk Utility

After the installer starts, macOS Utilities should appear.

For a clean installation:

1. Select Disk Utility.
2. Click Continue.
3. Choose View → Show All Devices.
4. Identify the Mini's internal drive.

Do not confuse the internal drive with the USB installer.

If you intend to preserve existing data, stop here and confirm your backup strategy. The following procedure erases the selected internal drive.

4.4 Erase and Format the Internal Drive

1. Select the internal physical disk in Disk Utility.
2. Click Erase.
3. Enter a name for the drive.
4. Choose GUID Partition Map, if the Scheme option is available.
5. Choose the appropriate format:

- APFS for an SSD. - APFS is generally appropriate for Catalina installations on modern compatible storage. - For older spinning hard drives, consult Apple's Catalina installation guidance and Disk Utility's available choices before proceeding.

6. Confirm that the selected disk is the intended internal drive.
7. Click Erase.
8. Wait for the operation to complete.

We named our newly prepared drive Mini HD.

The exact format should be chosen based on the installed storage hardware and the Catalina installer requirements. Do not assume every older Mac has the same drive configuration.

4.5 Install macOS Catalina

1. Quit Disk Utility to return to macOS Utilities.
2. Select Install macOS.
3. Click Continue.
4. Follow the installation prompts.
5. Choose Mini HD as the destination.
6. Allow the installation to finish.

The computer may restart several times.

Do not disconnect the installer or interrupt power unless the installation instructions explicitly direct you to do so.

Installation time depends on the Mini's internal drive and overall condition.

4.6 Complete Initial Setup

After Catalina starts:

1. Select your language and region.
2. Configure networking as appropriate.
3. Create a dedicated local maintenance administrator account with a strong password.
4. Do not sign in with a personal Apple Account or enable personal iCloud synchronization.
5. Review privacy and analytics options.
6. Finish the initial desktop setup.
7. Once the installation is complete, create a separate standard (non-administrator) Mini Operator account for routine camera and file-management tasks.

Keep administrator credentials for maintenance and software installation. Use the standard account for ordinary operation whenever permissions allow. File Sharing and remote-access permissions will be configured separately in later chapters.

Our goal was to avoid unnecessarily exposing personal iCloud information on a computer kept in the garage. Security limitation: macOS Catalina no longer receives current security updates, so keep the Mini's network exposure minimal and do not use it for sensitive personal accounts.

4.7 Verify the Installation

Once the desktop appears:

1. Open Apple menu → About This Mac.
2. Confirm that macOS Catalina 10.15 is installed.
3. Open Finder and verify that Mini HD is available.
4. Test the keyboard and mouse.
5. Confirm that the USB ports function.
6. Check that Wi-Fi and Ethernet are recognized.
7. Restart the Mini once to confirm that it can start from its internal drive.

At this stage, the Mini should function as a basic standalone Mac.

Network sharing and remote access will be configured in later chapters.

4.8 Startup Troubleshooting

4.9 What We Learned

The most important lesson from this phase was not about Catalina.

It was about troubleshooting assumptions.

We initially had what appeared to be a bootable USB problem. In practice, the original wireless keyboard prevented us from selecting the installer.

Changing the keyboard allowed the installation to proceed.

When an older computer refuses to start from installation media, verify the simplest components before rebuilding everything.

Sometimes the computer is fine.

Sometimes the installer is fine.

Sometimes the keyboard has simply decided not to participate.